1. Technical Field
The present invention relates to a semiconductor device, a medical instrument, and the like.
2. Related Art
Similar to an ejecting head which is mounted in an ink jet printer, there are many actuators constituted by a capacitive load, such as a piezoelectric element. In order to drive an actuator as a capacitive load, a drive signal having a certain level of power is required. Accordingly, a drive waveform signal as a source of a drive signal is power-amplified to generate a drive signal. When an analog drive waveform signal is power-amplified in an analog form to directly generate an analog drive signal, significant power loss occurs and power efficiency is degraded. Accordingly, technology for power amplification using a so-called class D amplifier has been suggested.
A medical instrument which uses a fluid transport apparatus, in which a plurality of rollers are provided on a concentric circle of a rim portion of a rotor, a tube is mounted such that a fluid flows between the tube and a tube receiving member, and when the rotor rotates, the rollers sequentially press the tube to cause the fluid to flow, is known. A medical instrument which uses a fluid transport apparatus, in which the tube is pressed to cause the fluid to flow using a plurality of pressing elements (for example, piezoelectric elements) instead of a plurality of rollers, or a medical instrument which uses a fluid ejecting apparatus using a piezoelectric element is also known.
For example, when a switching circuit, such as a class D amplifier, is used as a circuit which drives a plurality of piezoelectric elements, in order to suppress ringing of an output voltage, in general, a bypass capacitor is arranged between a power supply potential and a ground potential (for example, JP-A-2011-187809). In an ink jet printer, the occurrence of ringing leads to the occurrence of EMI noise. As a result, the amount of ink to be ejected varies, thereby causing interference with improvement in printing quality. In a medical instrument using a fluid transport apparatus or a fluid ejecting apparatus, the occurrence of ringing leads to the occurrence of EMI noise, causing interference with the operation of the apparatus itself or peripherals. For example, in a medical instrument using a fluid ejecting apparatus, the occurrence of EMI noise with ringing causes variation in the amount of fluid to be ejected.
In order to suppress ringing, it is important to decrease parasitic inductance in a loop having two transistors and a bypass capacitor of a switching circuit. In order to decrease parasitic inductance, it is necessary to decrease the area of a loop having two transistors and a bypass capacitor of a switching circuit. The inter-electrode distance of the capacitor increases with an increase in capacitance of the capacitor, and thus, in the arrangement of the capacitor described in JP-A-2011-187809, an increase in capacitance of the capacitor results in an increase in the area of the loop. For this reason, there is a limitation to suppress ringing, that is, to improve printing quality or to stably transport a fluid.